Yes, he is talking about the right click (power) menu. I don't have high contrast myself. All the Windows 10 computers I have encountered so far have a black background. Now you have wound me up. I am going to need to dive into my computer and try and change mine!
There is a hidden dark theme that I was going to post above in which requires a registry modification, but it only applies to the settings window and apps. I have not yet updated, but I'm fairly sure that it's an option with the new latest builds of Windows 10 with context menu options. I'm currently installing 10586 via Windows Updates as I post this.
Thanks for the suggestion. I stay away from reg mods. If I cant do it through the settings, then I feel it is best left alone.
Mike. Stranger and stranger. I have just experimented. Mine seems to be the other way around. High contrast (The first time I have ever ventured into that, with Windows 10), gives me the white background, but, unfortunately, I cannot then adjust a few other colours to my liking. Interesting though.
I am running build 10586 and it appears that the power menu is black by the settings I currently have. No visible settings added to the personalization menu however so I'm not sure if it has something to do with an existing theme option or not. It's very late however and I need to go to sleep.
One interesting thought, on the W10 machine I'm writing this (v1511:b10586.29), W10 is not activated, and you cannot change Themes, or backgrounds (wallpapers), or much of anything else unless your W10 is activated. Did you perform an upgrade from an earlier version of Windows (such as Win7 or Win8/8.1)? Was that Windows version licensed? Or did your PC come with W10 pre-installed? If so, your upgrade to W10 should now be also Activated. If you type in "THIS PC" next to the W10 Start Flag in the lower left of your W10 desktop, and click on "Properties", look under "Windows Activation". If not activated, you won't be able to make any changes to your desktop.
However, if your Windows Activation shows "Activated", then you have the ability to change your themes as mentioned above. Haven't tried to change this submenu myself, so I don't know about that yet; but will look into it and report back. Letting us know which state your W10 is in (Activated or Not-Activated) may help us to track down the issue.
P.S. Since things like desktop themes, backgrounds, etc. are linked to W10 desktop, it is an "Active" desktop, which means any changes you make on the "Activated" W10 machine will propagate to all other W10 machines you have. If you could change this submenu to another color, it will be forced to change on automatically on all your other W10 machines as well.
Well I'm running 10586.29 and right-clicking on the Start Menu (or Windows Key + X) gives me the black-grey command menu too. I don't think this was a thought when they were changing the context menus, as it is more of a administrative function. They probably want to make sure it renders properly no matter what color scheme has been set? Hmm?